In COO, cooperation is a problem of synchronization among development activities running in parallel. We propose to encapsulate development activities within COO-transactions to ensure general properties on their concurrent execution. We have developed a new correctness criterion called COO-serializability which ensures consistency property in a cooperative context. COO-serializability is purely syntactic criterion based on the log analysis of repository access. In this paper, we describe COO-serializability foundation and how to evaluate it incrementally using the COO-protocol. Finally, we describe how we have implemented the COO-protocol in the COO environment.